It is safe and it could cause u to depends on how u have sex like the position and how hard u have sex just saying it honestly does
Im 36+2 n i am 3cm dilated and 50 effaced.. i say go for it i did with my other 3 pregnancies and very same night went into labor im not saying it works right away but it may help and as long as ur water hasnt broke its safe of course you should also be comfortable doing it and if ur not then maybe jus wait your almost done.. i wish you the best of luck and hope you deliver soon.
Its safe as long as your dr has not told you to stay away from it. & if I was you I'd be hoping it'd put me in labor! Lol I'm 38+1 & still 0!